Process of Producing Manganese Cast Steel on High Impact Strength

ABSTRACT

A process for producing austenitic Hadfield type manganese steel of high impact resistance by adding to molten manganese steel 0.01% - 0.5% antimony. Austenitic manganese steel of the Hadfield type with an antimony content of 0.01% to 0.5%.

United States Patent [1 1 Sakwa et al.

[ 51 Feb.4,1975

22 Filed: July 28, 1971 21 App1.No.: 166,958

Related US. Application Data [63] Continuation-impart of Ser. No. 771,619, Oct. 29,

1968, abandoned.

[30] Foreign Application Priority Data Oct. 31, 1967 Poland 123320 [52] US. Cl 75/129, 75/123 A, 75/123 N [51] Int. Cl... C22c 33/00, C22c 39/30, C22c 39/54 [58] Field of Search... 75/123 J, 129, 123 A, 123 N,

75/126 N, 126 B, 128 A, 128 R [56] References Cited UNITED STATES PATENTS Hodson 75/123 A' 2,334,870 11/1943 Franks 75/126 N X 2,867,531 1/1959 Holzwarth et al. 75/123 A 3,113,861 12/1963 Norman 1. 75/1231 FOREIGN PATENTS OR APPLICATIONS 1,213,418 11/1970 Great Britain 75/123 A 663,986 5/1963 Canada 75/123 N OTHER PUBLICATIONS A Dictionary of Metallurgy by A. D Merriman, 1958, pp iii & 179.

Primary Examiner-L. Dewayne Rutledge Assistant Examiner-Peter D. Rosenberg [57] ABSTRACT A process for producing austenitic Hadfield type man ganese steel of high impact resistance by adding to molten manganese steel 0.01% 0.5% antimony. Austenitic manganese steel of the Hadfield type with an antimony content of 0.01% to 0.5%.

5 Claims, No Drawings PROCESS OF PRODUCING MANGANESE CAST STEEL ON HIGH IMPACT STRENGTH CROSS REFERENCE TO RELATED APPLICATION This application 'is a Continuation-ln-Part Application of US. Pat. Ser. No. 771,619, filed Oct. 29, 1968 now abandoned.

Manganese is well known as an alloying component in steel making. Authorities recognize two classes of manganese steel:

1. low manganese steel where the manganese content is up to about 2%, and

2. high manganese steel where the manganese content is about ll% to 14%.

The latter is cast, and is austenitic. The present invention is directed to improvements in high manganese, cast austenitic steel, which is that steel discussed in the following two paragraphs.

Manganese steel, as set forth in Metallurgy and Its Influence On Modern Progress" by Sir Robert A. Hadfield, 1925, is steel which has a manganese content in the range of about 11 14% and a carbon content in the range of about 1.0 1.5%: such steel as cast" is austentic Hadfield U.S. Pat. No. 1,310,528 defines Manganese Steel as steel having a manganese content of about to 17% manganese, with carbon in the range of 0.75 2.0%.

In a former technique manganese cast steel is produced by a basic metallurgical process. Into a liquid metal the following non-ferrous metals are introduced: aluminum in order to deoxidize the bath and for refining the original structure, and titanium for bonding nitrogen in a stable intermetallic compounds.

This cast steel in a crude state shows an austenitic structure with several carbide inclusions.

In order to obtain a uniformaustenitic structure, without the presence of carbides, cast steel is heat treated by soaking it at a temperature range of 1323 1355K and subsequently cooling it in water.

The process of producing cast steel of high impact strength according to the invention comprises melting manganese cast steel in the known manner and then modifying it with antimony in the amount of 0.01 0.5%.

The modification can be carried out in a furnace or in a ladle. In introducing the modifying agent into a furnace before tapping, the slag should be skimmed in order to enable the direct introduction of the antimony into the metal bath.

Owing to this modification an austenitic structure with small amounts of carbide inclusions can be obtained.

The heat treatment of casting of such cast steels is carried out at the same temperatures but in considerably shortened annealing period or at lower temperatures (l223 1273K) in the same annealing period.

The impact resistance of manganese cast steels obtained from the process according to the present invention are about 20 200% higher than that of cast steels produced according to previous techniques.

Manganese cast steel after being heat treated (soaked for 1 hour at the temperature of 1323K) shows mean impact strength of a sample without a notch as follows: without addition of Sb 254 J/cm 26 kGm/cm with addition of 0.05% Sb 490 .l/cm

- 50 kGm/cm We claim:

l. A process for producing austenitic cast steel having a high impact strength comprising adding to molten high manganese steel approximately 0.01 to 0.05% antimony.

2. The process of claim 1, wherein said molten high manganese steel is in a furnace and has slag thereon, and wherein said slag is skimmed off and said antimony is introduced directly into the molten steel bath.

3. The process of claim 1, wherein said antimony is added to said steel while said steel is in a ladle.

4. The process of claim 1, wherein said high manganese steel contains approximately 10 to 17% manganese, approximately 0.75% 2.0% carbon and is sub stantially austenitic when cast.

5. Austenitic cast high manganese steel having an antimony content of about 0.01 to 0.05%.

=l l l 

2. The process of claim 1, wherein said molten high manganese steel is in a furnace and has slag thereon, and wherein said slag is skimmed off and said antimony is introduced directly into the molten steel bath.
 3. The process of claim 1, wherein said antimony is added to said steel while said steel is in a ladle.
 4. The process of claim 1, wherein said high manganese steel contains approximately 10 to 17% manganese, approximately 0.75% -2.0% carbon and is substantially austenitic when cast.
 5. Austenitic cast high manganese steel having an antimony content of about 0.01 to 0.05%. 